This invention relates to the hydrotreating, preferably hydrodesulfurization, hydrodenitrogenation, and combinations thereof, using a bulk multimetallic catalyst comprised of at least one Group VIII non-noble metal and at least two Group VIB metal wherein the ratio of Group VIB metal to Group VIII metal is from about 10:1 to 1:10.
As the supply of low sulfur, low nitrogen crudes decrease, refineries are processing crudes with greater sulfur and nitrogen contents at the same time that environmental regulations are mandating lower levels of these heteroatoms in products. Consequently, a need exists for increasingly efficient desulfurtion and denitrogenation catalysts.
A family of compounds related to hydrotalcites, e.g., ammonium nickel molybdate, has been prepared as an approach to improved hydrotreating catalysts. Whereas X-ray diffraction analysis has shown that hydrotalcites are composed of layered phases with positively charged sheets and exchangeable anions located in the galleries between the sheets, the related ammonium nickel molybdate phase has molybdate anions in interlayer galleries bonded to nickel oxyhydroxide sheets. See, for example, Levin, D., Soled, S. L., and Ying, J. Y., Crystal Structure of an Ammonium Nickel Molybdate prepared by Chemical Precipitation, Inorganic Chemi , Vol. 35, No. 14, p. 4191-4197 (1996). The preparation of such materials also has been reported by Teichner and Astier, Appl. Catal. 72, 321-29 (1991); Ann. Chim. Fr. 12, 33743 (1987), and C. R. Acad. Sci. 304 (II), #11, 563-6 (1987) and Mazocchia, Solid State Ionics, 63-65 (1993) 731-35.
Consequently, a need exists for increasingly efficient desulfurinzation and denitrogenation catalysts.
In accordance with this invention there is provided a process for hydrotreating raw virgin petroleum distillates, which process comprises contacting a feedstock comprised of at least about 50 wt. % raw virgin distillate, at hydrotrating conditions, with a bulk multimetallic catalyst comprised of at least one Group VIII non-noble metal and at least two Group VIB metals and wherein the ratio of Group VIB metal to Group VIII non-noble metal is from about 10:1 to about 1:10.
In a preferred embodiment of the present invention the Group VHI non-noble metal is selected from Ni and Co and the Group VIB metals are selected from Mo and W.
In another preferred embodiment of the present invention two Group VIB metals are present as Mo and W and the ratio of Mo to W is about 9:1 to about 1:9.
In yet another preferred embodiment of the present invention the bulk multimetallic is represented by the formula:
(X)b(Mo)c(W)dOz
wherein X is one or more Group VIII non-noble metals, and the molar ratio of b: (c+d) is 0.5/1 to 3/1, preferably 0.75/1 to 1.5/1, more preferably 0.75/1 to 1.25/1.
In still another preferred embodiment of the present invention the molar ratio of c:d is preferably  greater than 0.01/1, more preferably  greater than 0.1/1, still more preferably 1/10 to 10/1, still more preferably 1/3 to 3/1, most preferably substantially equimolar amounts of Mo and W, e.g., 2/3 to 3/2; and z =[2b +6(c+d)]/2.
In another preferred embodiment of the present invention the bulk catalyst is essentially amorphous and has a unique X-ray diffraction pattern showing crystalline peaks at d =2.53 Angstroms and d =1.70 Angstroms.
In still another preferred embodiment of the present invention the Group VIII non-noble metal is nickel.